OpenClaim

Nalmefene Side Effects

The most commonly reported side effects of nalmefene include coma, toxicity to various agents, and drug withdrawal syndrome, based on 312 FDA adverse event reports from 2004 to 2025. 24.4% of reports found the drug to be ineffective.

Nalmefene side effects

Percentages show how often each reaction appears relative to total reports for nalmefene.

1
Drug Ineffective24.4%76
2
Coma19.9%62
3
Toxicity To Various Agents17.0%53
4
Drug Withdrawal Syndrome12.8%40
5
Drug Interaction11.5%36
6
Hypotension8.3%26
7
Respiratory Depression8.0%25
8
Bradycardia6.7%21
9
Depressed Level Of Consciousness6.4%20
10
Hepatotoxicity6.1%19
11
Acute Kidney Injury5.4%17
12
Off Label Use5.1%16
13
Muscle Spasms4.8%15
14
Agitation4.8%15
15
Bradypnoea4.8%15

These are voluntary reports and do not establish that nalmefene caused these reactions.

Report severity

95.8%Serious299 reports
56.4%Hospitalizations176 reports
28.5%Fatal89 reports

Seriousness is determined by the reporter, not by OpenClaim.

Nalmefene drug interactions

Other drugs that appear in adverse event reports alongside nalmefene. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Naloxone-hydrochloride21.2%66
2
Fentanyl9.3%29
3
Buprenorphine8.3%26
4
Propofol7.1%22
5
Epinephrine6.7%21
6
Diazepam6.4%20
7
Fluoxetine-hydrochloride5.1%16
8
Atenolol4.8%15
9
Sertraline-hydrochloride4.5%14
10
Baclofen4.2%13
11
Methadone-hydrochloride3.8%12
12
Calcium3.8%12
13
Aripiprazole3.5%11
14
Eszopiclone3.5%11
15
Oxycodone3.2%10

Taken alongside

1
Levothyroxine-sodium6.1%19
2
Bisoprolol-fumarate5.8%18
3
Atorvastatin-calcium4.8%15
4
Aspirin4.2%13
5
Pantoprazole-sodium4.2%13
6
Omeprazole4.2%13
7
Furosemide3.5%11
8
Rivaroxaban3.5%11
9
Amiodarone-hydrochloride3.2%10
10
Betamethasone2.9%9
11
Trimeprazine-tartrate2.9%9
12
Hydrochlorothiazide2.6%8
13
Levodopa2.6%8
14
Levetiracetam2.2%7
15
Etanercept2.2%7

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports nalmefene side effects

40.1% of nalmefene adverse event reports involve female patients and 46.5% involve male patients. The largest age group is adult at 68%. These figures reflect who reports side effects, not underlying risk.

Sex

Female40.1%
Male46.5%
Unknown13.5%

Age group

< 21.6%
2–113.1%
12–172.8%
18–6467.7%
65+24.8%

What is nalmefene used for

Conditions and purposes for which patients were taking nalmefene when the adverse event was reported.

Alcohol AbuseAlcohol ProblemAlcohol UseAlcohol Withdrawal SyndromeAlcoholismAnalgesic TherapyAlcohol Withdrawal SyndromeAlcoholismAttention Deficit Hyperactivity DisorderDependenceDepressionDrug DetoxificationDrug TherapyDrug Use DisorderDrug Use For Unknown Indication

Showing 15 of 39 indications

Nalmefene brand names and reporting trend

Nalmefene is sold under the brand name Revex.

Brand names

Revex1

Quarterly reports (20042025)

20042010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking nalmefene with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.